MARINE ENGINESThe Thornycroft 90 and 108 engines are both 4 cylinder 4 stroke high speed diesel units both engines having electrically operated heaterplugs to aid cold startingThe cast iro n crankcase with ri bbed sidewalls houses a forged steel crankshaft carried in three or five bearings respectivelyA full press ure wet sump lubric ation system is emplo yed with a full flowdetachable element type oil filter and integrated lubricating oil coolerThe cooling system is indirect and usually employs an engine mounted heatexchang er with a belt dr iven ra w wa ter pu mp This sy stem is known as I FWCinternal fresh water cooledAn optional system is EFWC external fresh water cooled This system utilizes theengine fresh water pump and usually employs skin tanks attached to the hull to serve as single belt driven alternator and fresh water pump drive include a manualbelt tensioning arrangement for low maintenance completes the package 904 Cylinder naturally aspirated 108 4 Cylinder naturally aspiratedPower intermittent at 3500rpm 36BHP Power intermittent at 3500rpm 47BHP continuous at 3000rpm 30BHP continuous at 3000rpm 38BHPMaximum torque at 2500rpm 531bf ft Maximum torque at 2400rpm 731bf ftIdle speed 570rpm Idle speed 570rpmMinimum full load speed 1500rpm Minimum full load speed 1500rpmENGINE RATINGSThe type 90 Engine may be set to develop continuous outputs from 135 to 30 BHP according type 108 Engine may be set to develop continuous outputs from 21 to 38 BHPaccording to special applications where full power will not be required for periods inexcess of 1 hour in any 12 hours consecutive running the engine can be supplied at anintermittent rating as shown aboveNOTE All horsepower ratings quoted are at the engine flywheel Due allowance mustbe made for transmission losses which will depend on the type of gearbox fittedFor tropical use it is necessary to derate the engine by 2 for each 5C 10Fabove 30C 85F air temperature at sea level In some parts of the wor ldfur the r de rat ing for h umi dity is n ece ssar y in acco rda nce withBS 55141 INITIAL STARTING OF ENGINEPAGE Engine mounting and dipstick marking Filling engine with oil 2 Lubricant specification for engine and gearbox Filling gearbox 3 inhibitor specification Filling cooling system 4 Priming the engine oil system 5 Bleeding the fuel system type 90 engines 6 Bleeding the fuel system type 108 engines 7 Initial start Normal start Running in 8 Operating guidelines 9 Operating guidelines MAINTENANCE Maintenance schedule Engine oil and filter change10 Engine oil and filter change11 Fuel filter change Cleaning Type 90 engines12 fuel lift pump Gearbox oil Type 108 engines13 change Cleaning air filter14 Alternator drive belt adjustment15 and replacement Raw water pump16 adjustment and replacement17 Checking and setting valve clearances Procedure for retorquing cylinder head nuts fuel injectors19 Changing coolant20 Draining raw water system21 External fresh water cooled engines22 Electrical system23 Fault finding24 Fault finding25 Laying up the engine26 Notes2829 CHECKING ENGINE MARKING DIPSTICK FILLING ENGINE WITH OILPage 1 CHECKING ENGINE MOUNTING The maximum installed angle of the engine is 15 engine types 902 108 and 1082 10 for engine type 90 This allows for a further rise of 4 when the craft is moving Check the angle of installation using the centreline of the mounting feet bolts as a datum Measure vertically on the centreline of the underside of the front mounting foot bolt to find the angle of installation Fig 1 Fig 1 Horizontal Line Type 90 Type 902 Type 108 A 93mm 10 A 138mm 150 A 136mm 15 46mm 5 93mm 10 91mm 10 46mm 5 46mm 5 MARKING DIPSTICK FILLING WITH OIL Your engine is despatched from the factory without engine or gearbox oil and with an unmarked engine dipstick After the boat is launched and is resting at its normal trim angle remove the oil filler cap from the rocker box Fig 2 and pour 39 litres for type 90 45 litres for type 902 or 48 litres for type 108 of specified lubricant through the filler hole Allow 5 minutes for the oil to drain into the sump withdraw the dipstick and mark it for maximum oil level Fig 3 Use a centre punch for marking as filing a notch can cause fatigue and eventual breakage while the engine is running Then mark dipstick using the same method 127mm below the maximum mark and this will be the minimum level LUBRICANT ENGINE AND GEARBOX THORNYCRO FT Page 2 ENGINE OILRUNNING IN OILSDo NOT use special runningin lubricating oils for new or rebuilt engines Use thelubricating oils specified for normal engine OIL VISCOSITY use of a multi graded lubric ating oil h as been fou nd to impro ve oilconsumption and improve engine cranking in cold temperatures while at high operating temperatures A multigrade oil conforming toMILL20104B is recommended with the viscosity grades shown in Fig 4 The use ofsingle grade lubricating oil is not recommended except for synthetic oils usedin arctic conditions Atmospheric Temperature Viscosity Above 10C 20W50 20C to 10C 1OW30 or 1OW40 Below 10C 5W30 or 5W40 Fig 4 GEARBOX OILBorg Warner Automatic Transmission Fluid T ype AHurth Automatic Trnamsission Fluid T ype ANewage PRM SAE 20 Engine Oil Minus 18C to 0C SAE 30 engine Oil Above 0C FILLING THE GEARBOXRemove the oil filler plug combined dipstick from the top of the gearbox This isin approximately the same position on Hurth Newage PRM and Borg Warner Usinga plastic bottle or funnel fill the gearbox up to the maximum mark on thedipstick There is one level mark on the Hurth dipstick the others have highand low marksFig 5THORNYCROFT COOLING SYSTEMPage 3 COOLANT Use antifreeze during all seasons to protect the engine cooling system from corrosion as well as freeze damage Using the following antifreeze solution 25 3 3 5 0 Solution Solution Solution Complete protection lOF12C 3F16C 4F20C Safe protection 1F17C 8F22C 18F28C In tropical climates where antifreeze availability may be limited corrosion inhibitor to protect the engine cooling system use a NOTE Corrosion inhibitor is NOT an antifreeze COOLANT QUANTITIES Complete system including engine IFWC types 90 and 108 engines 51 Litres For external fresh water cooled engines EFWC See Page 23 FILLING THE COOLING SYSTEM Remove the filler cap from the heat exchanger Fig 6 and fill the system with coolant This will take approximately 5 minutes as the system self bleeds Fill to 5mm below the filler neck level mark Refit filler cap M Fig 8 405ilI M Fig 9 PRIMING THE ENGINE OIL SYSTEM THOMYCWFT Page 4PRIMING THE ENGINE OIL SYSTEM TYPE 902R ENGINES ONLYAs only a residual amount of oil is present in the oil pump filter and oilgalleries of the engine it is therefore necessary to prime the system before theengine is run Connect the engine starter batteries disconnect power to thefuel solenoid valve on the injection pump Fig 7 and crank the engine over usingthe key starter switch until pressure registers on the oil pressure gaugeStop cranking and check the engine and gearbox for oil or water leaks Replacepower connector Fig 7PRIMING THE ENGINE OIL SYSTEM TYPE 90 AND108 ENGINESAs only a residual amount of oil is present in the oil pump filter and oilgalleries of the engine it is therefore necessary to prime the system before theengine is run Connect the engine starter batteries operate the key starterswitch with the stop control out crank the engine over until pressure registerson the oil pressure gauge Stop cranking and check the engine and gearbox foroil or water BLEEDING THE FUEL SYSTEM TYPE 90 ENGINESPage 5 BLEEDING THE FUEL SYSTEM Slacken the bleed valve on the injection pump Fig 8 Operate the lift pump Fig 9 and when the fuel coming from the valve is free of air bubbles tighten the valve Fig 8 Slacken the uni ons at the injector ends of a ny two high p ressure pipes Fig 10 Ensure that the stop control is in the run position and the engine speed control is in the fully open position Crank the engine until the fuel coming from both pipes is free from air bubbles then tighten the unions NB After initial start procedure has been observed start the engine and allow it to idle until it is running evenly on all four cylindersFig 10 BLEEDING THE FUEL SYSTEM TYPE 108 ENGINES THORNBLEEDING THE FUEL SYSTEM Fig 11 53 YCROF Fig 12 2 46 Note After renewing the fuel filter element it will only be necessary to bleed the fuel filter as described in 1 and 2 provided that the engine has not been cranked while the filter is dismantled 1 Slacken the blanking plug in the unused outlet connection in the fuel filter head Fig 12 Operate the lift pump Fig 9 page 5 until the fuel flowing from the plug is free of air bubbles tighten the plug NB Numbers 26 refer to Fig 11 bleed points 2 Slacken the union nut at the injection pump end of the fuel feed pipe Operate the lift pump and when the fuel flowing from the union is free from air bubbles tighten the nut 3 Slacken the air bleed screw on the injection pump body Operate the lift pump and when the fuel flowing from the bleed screw is free from bubbles tighten the screw 4 Slacken the air bleed screw on the injection pump governor housing Operate the lift pump until the fuel flowing from the bleed screw is free from air bubbles leave the bleed screw slack 5 Slacken the air bleed screw on the injection pump high pressure banjo bolt Operate the starter motor while operating the throttle control and when the fuel flowing from the high pressure bleed screw is free of air bubbles tighten the bleed screw 6 Co ntinue cranking the engine with the starter motor to expel any air trapped in th e governor and when the fuel flowing from the go vernor housing bleed screw is free of air bubbles tighten the screw Slacken the unions at the injector ends of any two high pressure pipes Fig 13 Ensure that the stop control is in the run position and the engine speed control is in the fully open position Crank the engine until the fuel comibng from both pipes is free from air bubbles then tighten the unions NB After initial start procedure has been observed start the engine and allow it to idle until it is running evenly on all four cylinders Fig 13THORNYCROFT INITIAL START NORMAL START RUNNING INPage 7 INITIAL START With all systems filled primed and checked the engine may be started Run it for 2 to 3 minutes then stop it Top up engine gearbox oil and water levels to the high mark The engine and gearbox are now ready for use Oil pressure should be observed within 15 seconds NORMAL STARTING PROCEDURE 1 Put gearbox selector lever in neutral 2 Ensure the stop control is fully disengaged 3 Set the engine speed control lever fully open 4 Turn the key to H position on starter switch and hold for 30 seconds this preheats the heater plugs This is not necessary for a warm engine Also control level only needs to be set half open 5 Turn the key to H S position and the starter motor will crank up the engine CAUTION If the starter fails to crank up the engine within 10 seconds re lea se t he s wit ch k ey a nd w ait for th e starter motor to come to a c o m pl et e st o p T h en tu r n t h e k e y to H S po s i ti o n a ga i n D o n o t engage the starter motor for more than 30 seconds then wait 2 minutes between unsuccessful attempts 6 Move the throttle position to idle as soon as engine starts 7 Oil pressure should be observed within 15 seconds 8 To stop the engine pull the stop control RUNNING IN The care given to an engine in the first 20 hours of operation will result in longer life better performance and more economical operation During this period follow these 1 Warm up the engine before placing it under load 2 Do not operate the engine at idle or full load for more than 5 minutes 3 Avoid constant speed 4 Observe oil pressure and temperature gauges 5 Check the oil and coolant levels frequently GENERAL PRECAUTIONS 1 NEVER attempt to start the engine with the gearbox control lever in any position other than neutral 2 NEVER stop the engine without first engaging neutral 3 When changing the control lever from ahead to astern or vice versa pause in neutral OPERATING GUIDELINES THORNYCROFT I Page 8COMPLIANCE WITH THE FOLLOWING CAN RESULT IN LONGER LIFE BETTER PERFORMANCE ANDMORE ECONOMICAL OPERATION OF YOUR perform all of the specified maintenance including the First Start ofthe Day checksUse antifreeze during all seasons to protect the cooling system from corrosion as well asfreeze damageNever operate the engine without a thermostatUse quality fuel that is free of water and other contaminants Monitor the oilpressure and temperature indicators frequently AVOID FULL WHEN THE ENGINE IS COLDWhen starting a cold engine bring the engine up to operating speed slowly toallow the oil pressure to stabilise as the engine warms upIf temperatures are below 0C 32F operate the engine at moderate speeds for 5 minutes beforefull loads are appliedAVOID IDLING THE ENGINE FOR MORE THAN 10 MINUTESLong periods of idling may be harmful to your engine because combustion chamber temperatures candrop so low that the fuel may not burn completely Carbon can then form which may clog theinjector spray holes and also cause valves and piston rings to stickAVOID OVERHEATING THE ENGINECo ola nt t emp era tur e mu st not ex ceed 99 C 210 F wi th a 70 kP a 10 p siexpansion tank cap AND A MINIMUM OF 50 mixture of ethyleneglycol and waterIDLE THE ENGINE A FEW MINUTES BEFORE ROUTINE SHUTDOWNAfter full load operation idle the engine 3 to 5 minutes before shutting it offto allow th e lu bricating o il and coola nt to car ry h eat away from thecombustion chamber bearings shafts etcAVOID LOW COOLANT TEMPERATURE operation at l ow coo lant temperat ure be low 60C 150F can beharmful to the engine Low coolant temperature can cause incomplete carbon and varnish to form that can damage piston rings and A lso th e unburnt fu el c an enter the crankcase di lut ing thelubricating oil causing rapid wear to other moving OPERATING GUIDELINESPage 9 DO NOT OPERATE THE ENGINE WITH LOW OIL PRESSURE When the engine is at normal operating temperature the minimum oil pressures required are Idle 570 RPM 1 bar 15 psi Full Speed and Load 23 bar 35 psi DO NOT OPERATE THE ENGINE WITH FAILED PARTS Practically all failures give some warning before the parts fail Be on the alert for changes in performance sounds and visual tipoffs that indicate either service or repair is needed Some important clues are Engine misfiring or vibrating severely Sudden loss of power Unusual engine noises Fuel oil or coolant leaks Sudden change in the engine operating temperature Excessive smoke Loss of oil pressure SAFETY PRECAUTIONS Saf ety i s bu ilt i nto eve r y en gin e ho wev er l ike any o the r mechanical device it can present serious threat to life and limb if imprudently operated and maintained Remember that the best safeguards again st accidents are to kee p ever mindful of the potential dangers and to always use good common sense MAINTENANCE SCHEDULE TH0RNYCROFT Page 10DAILY OR EVERY 10 HOURSCheck engine and gearbox oil levels top up if necessary Checkcoolant level and top up if necessary Check drive FIRST 25 HOURSRetorque cylinder head nutsChange the engine oil and renew engine oil filterCheck valve rocker drive belt tensionsCheck oil connections for leaksCheck water hose all electrical fuel filter elementCheck and service injectors as necessaryCheck and adjust engine idling speed as necessary Use a Thornycroft dealer Check fuelsystem for leaks ENGINES IN REGULAR USEEVERY 50 HOURSCheck electrolyte level in batteriesEVERY 200 HOURS OR YEARLYChange fuel filter elementChange engine oilChange engine oil filterCheck drive beltsCheck air cleaner and clean if necessaryCheck for oil or coolant leaksCheck fuel system for leaksCheck gearbox oil levelCheck and adjust idling speed as necessaryEVERY 400 HOURSIn addition to the 200 hour maintenance schedules change the gearbox oil Remove heaterplugs and remove carbon from each orificeEVERY 800 HOURSIn addition to the 200 hour and 400 hour maintenance schedules Adjust valverocker clearancesTest injectors for spray Use a Thornycroft dealerCheck all engine and gearbox connections Renew oilfiller cap on rocker cover ENGINES USED OCCASIONALLY HALVE THE HOURS RECOMMENDED AFTER FIRST 25 ENGINE OIL CHANGE TYPE 90 ENGINESPage 11 CHANGE ENGINE OIL Run the engine until it reaches normal operating temperature stop the engine then using the hand pump Fig 14 drain the oil into a suitable container Fig 14 CHANGE ENGINE OIL FILTER Slacken the centre fixing bolt 1 Fig 15 and withdraw the filter bowl 2 and filter element 3 together Discard the filter element andsealing ring 4Replace with new element and sealing ring ensuring that the ring iscorrectly seated i n t he filt er head 5 and tig hte n t he centre boltFill the engine with the specified amount of oil and prime the oil systemas described on Page 4Start the engine and check for oil leaks run the engine for 2 minutesensure pressure registers on the gauge Stop the engine and allow a fewminutes for oil to settle Check oil level top up if necessary Fig 15 ENGINE OIL CHANGE TYPE 108 ENGINES THORNYCRO FT Page 12CHANGE ENGINE OILRun t he engine u ntil it reaches nor maloperating temperature stop the enginethen using the hand pump Fig 16 drain theoil into a suitable container Fig 17 Unscrew the oil filter cartridge Fig 17 Discard the cartridge and its sealing ringLightly smear the sealing ring with cleanengine oil Fig 18 and screw the into place using hand pressureonly until the sealing ring abuts with thefilter head face Then tighten a further a of a turnFill the engine with the specified amount asof oil and prime the oil system described on Page 4Start the engine and check for oil leaks run the engine for 2 minutes ensurepressure register on the gauge Stop the engine and allow a few minutes forOil to settle Check oil level and top op if FUEL FILTER CHANGEPage 13 RENE W FUE L FILTER ELE MENT Turn off the fuel supply tap then support the filter base 1 Fig 1 9 and unscrew the centre bolt 2 Detach the base and twist the element 3 to separate it from the filter head 4 Remove the three sealing rings 5 from the head and base Discard element and sealing rings Clean base and head and assemble the filter using a new element and sealing rings Fit the element with its strengthened rim uppermost Turn on the fuel supply tap then bleed the air from the system as described on Page 5 or 6Fig 19 CLEANING FUEL LIFT PUMP THORWCT Page 14FUEL LIFT PUMP FILTERTurn off the fuel supply tap then remove the cap screw 1 Fig 20 Lift off the cap 2gasket 3 and filter gauze 4 Clean the gauze in a suitable solvent usin g asti ff brush Clean the fuel cham ber 5 Check that the gasket is serviceableor renew Assemble the components Do not overtighten the cap screw Neverclean inside fuel chamber or any other part of the fuel system with a fluffycloth Turn on the fuel supply tap then bleed the fuel system as described onPage 5 or 6Fig 20THORNYCROFT GEARBOX OIL CHANGEPage 1 5 CHANGING THE GEARBOX OIL T he gearbo x o il must be changed when the gearbox has reached operating temperature After about 12 hour driving the craft To help the oil drain easily from the gearbox first remove the oil filler dipstick plug from the top of the gearbox Place a suitable container under the gearbox and remove the drain plug from the underside of the gearbox and allow the oil to drain completely Fig 21 The drain plug is in approximately the same position on the underside of Hurth Borg Warner and Newage PRM gearboxes Refit the drain plug Fill the gearbox to the maximum mark on the dipstick Refit the filler plug start the engine in neutral and run the engine for 1 minute to allow the oil to circulate Stop the engine and check the oil level Top up if necessary to the maximum mark on the dipstick Fig 26Illustration shows PRM 160 gearbox Fig 27 CLEANING AIR FILTER THORNYC ROFT Page 16CLEANING AIR FILTERSlacken the clip on the breather pipe and pull the pipe off the air cleanerthen slacken the screw Fig 22 this allows removal of the outer casing and the air filter gauzeSubmerge the casing and gauze in a bath of clean paraffin or diesel fuel agitate themvigorously to remove dirt particles Shake the filter dry by hand or blow dry withcompressed air then refitFig 22 CAUTION WHEN USING A COMPRESSED AIR LINE GREAT CARE MUST BE OBSERVED AND GOGGLES MUST BE DRIVE BELT ADJUSTMENT AND REPLACEMENT ALTERNATOR AND RAW WATER PUMPPage 17 SAFETY BEFORE ATTEMPTING THESE OPERATIONS DISCONNECT THE STARTER BATTERIES Adjusting Alternator Drive Belt Type 90 alternator is shown in the illustration Fig 23 but procedure for adjusting the alternator drive belt is the same for type 108 engines Slacken the nuts and bolts 14 Move alternator away from the engine until the deflection of the belt arrowed is 19mm 075 in when pressed using finger pressure only at the longest point between pulleys Excessive tension will cause early wear of the belt water pump bearing and alternator bearing While a slack belt will slip causing overheating of the engine and insufficient charging of the batteries Check deflection after retightening Replacing Alternator Drive Belt Slacken the nuts and bolts Fig 23 14 move alternator in towards engine Remove old belt from pulleys and replace with new drive belt Retighten nuts and bolts Following the instructions above readjust the drive belt tension Fig 23 Adjusting Raw Water Pump Drive Belt Slacken the nuts and bolts Fig 24 1 and 2 an d ret ens ion the b elt as described above for the alternator The deflection of the belt must be 1012mm 039047in Check deflection after retightening Replacing Raw Water Pump Drive Belt Slacken the nuts and bolts Fig 24 1 and 2 Move pump in towards engine Remove old belt from pulleys and replace with new drive belt Retighten nuts and bolts following the instructions above readjust the drive belt tension Fig 24 CHECKING AND SETTING VALVE CLEARANCE THORWCWFT Page 18SAFETY BEFORE ATTEMPTING THIS OPERATION DISCONNECT THE STARTER Valve Clearances Engine ColdSlacken the rocker cover bolts and remove rocker cover Discard the gasket Turnthe crankshaft in the normal direction of rotation and adjust as followsSlacken the locknut and adjust with a screw driver until the correct clearance isobtained Fig 25 Insert the feeler blade between the valve stem and rocker armWhen correct adjustment is obtained the feeler blade is able to be removed withslight in the following sequence Set No 1 tappet with No 8 valve fully open Set No 3 tappet with No 6 valve fully open Set No 5 tappet with No 4 valve fully open S et No 2 tappet with No 7 valve fully open Set No 8 tappet with No 1 valve fully open Set No 6 tappet with No 3 valve fully open Set No 4 tappet with No 5 valve fully open Set No 7 tappet with No 2 valve fully open Rec hec k the clearance wit h the loc knu ts tightened and readjust if necessary Fig 25 Valve Clearance Type 90 engines Inlet Valve 0381mm 0015in Exhaust Valve 0381mm 0015in Valve Clearance Type 108 engines Up to Thornycroft Engine No 6043 Inlet and Exhaust 043mm 0017in Engine No 6043 onwards Inlet and Exhaust 035mm 0014inFit the rocker cover using a new gasket Tighten the boltsReconnect the battery start the engine and check the rocker cover for leaks THORNYCROFT PROCEDURE FOR RETORQUING CYLINDER HEAD NUTS Page 19 1 PROCEDURE FOR NEW ENGINES WHICH HAVE RUN FOR 25 HOURS A Run engine and stop when normal operating temperature is reached B Slacken the cylinder head nuts by approximately 16 of a turn one flat of the nut following the sequence shown using service tool 18G 1457 to reach the nuts in the centre rowFig 26 C Tighten the nuts in the sequence shown to 104 kgf m 75 lb ftI 11 6 5 12 00 00 0o 90 0 9 0 1 0 A OQ 1 13 14 107 3 1 4 89 Slacken the valve rocker pedestal nuts by 16 of a turn one flat of the nut and retorque to 35 kgf m 25 lb ft Adjust valve rocker clearances Page 182 PROCEDURE WHERE PART ENGINES HAVE BEEN FITTED OR WHERE CYLINDER HEADS ARE REMOVED OR REPLACED DURING REPAIR OPERATIONS A The cylinder head nuts should not be more than finger tight until the rocker shaft assembly has been fitted Tighten the nuts to 104 kgf m 75 lb ft type 108 engines 98 kgf m B 71 lb ft type 90 engines in the sequence shown in procedure 1 Using service tool 18G1457 to reach centre row Fig 27 C Tighten the valve rocker pedestal nuts to 35 kgf m 25 lb ft D Adjust the valve rocker clearance as in procedure 1When the engine has run f or Y2 hour carr y out the operat ion descr ibed inprocedure 1Fig 27 REMOVAL AND REFITTING FUEL INJECTORS THORNY CROFT Page 20REMOVING FUEL cleaning and spray testing can only be carried out with therefore this must be done by a Distributor or DealerFig 28 Disconnect the feed pipe 1 and spill rail 2 Note the sealingwashers 3 on each side of the spill rail banjo union Remove the bolts 4 and withdraw the injector Fit protective caps to all Fig 29Fig 28REFITTING FUEL protective caps Ensure the washers are fitted to the injectors asshown in Fig 29 It is most important to tighten the injector fixings evenly andto the correct torque of 165 kgf m 12 lbf ft overtightening or of the injector can distort the nozzle and will usually cause amisfire to occur when normal running temperature is reached Reconnect theinjector pipes do not overtighten the unions TO REMOVE HEATER PLUGS AND CLEAN ORIFICES Disconnect the battery Remove electrical leads 1 Fig29A and unscrew each plug 2 from th e cylinder head Insert a twist drill of 437mm 11 64 in dia 3 into t he th rea ded holes in the head 4 Turn the drill by han d to r emo ve car bon bui ld up Remove the drill and clean any particles of carbon from conical seatings in the cylinder head Refit the heater plugs and e lec tri cal l ead s Re connec t TAT CHANGING COOLANTPage 21 CHANGING COOLANT Remove filler cap from heat exchanger place a suitable container beneath the drain plug Fig 30 Remove plug and allow to drain Place suitable container beneath drain tap in cylinder block Fig 31 Remove tap and allow to drain Replace both plug and tap then refill with coolant of the correct strength for conditionsto be encountered See Page 3Fig 30iFig 31 DRAINING RAW WATER SYSTEM Page 22DRAIN THE RAW WATER SYSTEMSlacken the six screws Fig32 on the raw water pump Remove end covers fromheat exchanger and drain tubes either by removing the tube stack or by blowing outwith compressed air Remove oil cooler and drain tubes or blow out withcompressed air Alternatively disconnect raw water pipework before gearbox oilcooler and pipe from oil cooler into a container of antifreeze mixture andflush through system returning antifreeze mixture from water injection bendback into container this ensuring that any water pockets contain antifreeze CAUTION WHEN USING A COMPRESSED AIR LINE GREAT CARE MUST BE OBSERVED AND GOGGLES MUST BE WORNNOTE ANTIFREEZE MIXTURE MUST BE OF CORRECT STRENGTH FOR CONDITIONS TO 32ROUTINE MAINTENANCE OF RAW WATER SYSTEM IFWCTHESE NOTES DO NOT APPLY TO EXTERNAL FRESH WATER COOLED ENGINESExamine and clean the sea inlet strainer at regular intervals Do Not remove thestrainer when the engine is running as foreign matter can be drawn into the system and damage to the pump The sea cock must be FULLY OPEN when the engineis running If the sea cock is partially closed air can be drawn in withconsequ ential failure of the raw water pump and engine overheating Check theraw water discharge pipe immediately after starting the engine to see if the raw waterpump is functioning The engine MUST NOT run without a flow of raw water through the heat exchangerRAW WATER PUMP the raw water pump is self priming and fitted with a It depends on the raw water for its lubrication DO NOT run dryM ore than 3 0 se con ds runn ing withou t wate r will b urn the impellor and becontributory to an early failure When replacing the end cover gasket it isessential to use the correct part variation of the gasket thickness can cause loss ofselfpriming ability or seizure EXTERNAL FRESH WATER COOLED ENGINES ONLY 2 3 This consists of a closed circ uit fresh water system with a fre sh water circulator combined header tank and exhaust manifold dry exhaust outlet and watercoolant tanks normally fitted to the skin of the craft It is therefore important when filling this system with antifreeze solution or corrosion inhibitor that the total capacity of the tanks associated pipework and the engine cooling system is taken into consideration Your boat builder will advise you on these figures We have included the box below for you to fill in these figures for your craft Name of Craft External Fresh Water Cooled System Capacity Date Change Due ELECTRICAL SYSTEM THORNYCROFT Page 24Electrical SystemAn insulated return system is employed on the type 90 and 108 enginesThe 12 volt alternator has a builtin voltage regulator which the charging rate to provide sufficient electric current to keep thebattery fully charged under normal operating conditionsThe alternator requires no lubrication maintenanceDo NOT disconnect the battery leads while the engine is runningEnsure that the correct battery terminal is connected to a good earth on thestarterA coating of a good grade of petroleum jelly will protect the terminals electrolyte level should be 6 to 9mm 025 to 038in above the top of the plates If theelectrolyte is below the correct level add the required amount of water for battery use should be kept in clean covered In cold weather add water only immediately before running the engine sothat the charging will mix the water and electrolyte and prevent freezingIf t he b att ery i s al lowed to sta nd at lo w tem per atu res in a p art ial lydischarged condition there is a possibility that it may freeze causing damage to the container Takecare therefore to keep the battery as fully charged as possibleThe specific gravity of the electrolyte when the battery is fully chargedshould be 1275 at a temperature of 25C 77F At differing temperatures the specific gravityof a fully charged battery will change The specific gravity of any given temperaturecan be calculated by subtracting 0004 from 1275 for every 6C change above 25C and adding 0004 to1275 for every 6C below 25CKeep the battery filler plugs and connections tight and the top of the battery clean Wipingthe battery with a rag moistened with ammonia will counteract the effect of anyof the solution which may be on the outside of the battery Wear when carrying out this operation If ammonia is accidentally splashed in theeyes wash out thoroughly at once with clean water and SEEK QUALIFIED MEDICAL Jumper CablesTo avoid the possibility of extensive damage to your charging system it isimportant to observe the following points when using battery jumper cables to start an enginehaving a discharged battery The positive terminals of the batteries must be one cable usually red and the negative terminals the other cable If this procedure is not followed extensive damage may bedone to the charging systemCAUTION Since explosive hydrogen gas is always present sparks or flames should not be allowed near the battery When using jumper cables the cables should always be attached to the booster battery FAULT FINDINGPage 25 FAULT FINDING ENGINE WILL NOT START Starter does not ELECTRICAL FAULT crank engine Battery run down Lead disconnected Faulty starter switch Faulty starter motor Starter cranks ELECTRICAL FAULT engine slowly Battery partly run down Terminals loose Connections dirty Faulty starter motor MECHANICAL FAULT Wrong grade engine oil Starter cranks ELECTRICAL FAULT engine normally Faulty glow plugs Faulty wiring connection MECHANICAL FAULT Injection timing incorrect Poor cylinder compression Blocked air intake FUEL FAULT Fuel Not Reaching Injection Pump Insufficient fuel in tank Blocked fuel pipeline Blocked fuel tank vent Restricted fuel filter Air leaks in pipeline Fuel Reaching Injection Pump Air in fuel system Faulty injectors